JP2018056723A - Imaging element and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a correction data amount at the time when an image signal is corrected.SOLUTION: A correction data retention unit holds a correction value of an end part pixel that is a pixel arranged at an end part of a pixel array part in which pixels each outputting an image signal depending on emitted light are arranged in a matrix, among correction values used for correcting image signals outputted from pixels arranged at a peripheral edge part as a region in the vicinity of the end part of the pixel array part, and also holds a distance from a boundary of a region other than the peripheral edge part in the peripheral edge part and the pixel array part to the end part. A correction value generation unit generates a correction value in the pixel arranged between the end part pixel and a peripheral edge part boundary pixel that is a pixel arranged at the boundary, on the basis of the held correction value and distance. A correction unit corrects the image signal on the basis of the correction value.SELECTED DRAWING: Figure 1

Description

  The present technology relates to an imaging element and an imaging apparatus. Specifically, the present invention relates to an imaging device and an imaging apparatus that correct an image signal.

  2. Description of the Related Art Conventionally, there has been known a phenomenon in which an image output from an imaging apparatus has uneven brightness in a screen and image quality is deteriorated. This phenomenon is referred to as shading, and is a phenomenon that occurs when the sensitivity of pixels arranged in an image sensor used in an imaging apparatus is not uniform in the screen. This shading also occurs when the incident angle of light differs between the central portion and the peripheral portion of the image sensor due to the influence of the lens that forms an image on the image sensor. In view of this, an imaging apparatus that prevents the occurrence of shading by correcting the image signal output from the imaging element is used. For example, there has been proposed a system that corrects an image signal by dividing a pixel into a plurality of blocks, setting correction data for each block, and smoothing the correction data using a two-dimensional filter to generate correction values. (For example, refer to Patent Document 1).

JP 2007-116724 A

  In the above-described conventional technique, correction data set for each block is stored in the correction data interpolation memory. In order to improve the image quality after correction, it is necessary to subdivide the blocks, and the number of blocks increases. Also, the number of blocks increases when the above-described conventional technology is applied to an image sensor with high definition. For this reason, the above-described conventional technique has a problem that the amount of correction data stored in the correction data interpolation memory increases.

  The present technology has been created in view of such a situation, and aims to reduce the amount of correction data when correcting an image signal.

  The present technology has been made to solve the above-described problems. The first aspect of the present technology is that pixels that output an image signal corresponding to irradiated light are arranged in a matrix shape, and a central portion and a peripheral edge. Among the correction values when correcting the image signal output from the pixel arranged at the peripheral portion of the pixel array portion having a portion, the end pixel which is the pixel arranged at the end portion of the pixel array portion A correction data holding unit that holds the correction value and the distance from the edge to the boundary between the central part and the peripheral part, and arranged at the edge pixel and the boundary based on the held correction value and distance An imaging device comprising: a correction value generation unit that generates the correction value in a pixel that is arranged between the peripheral edge pixel that is a pixel that has been corrected; and a correction unit that corrects the image signal based on the correction value It is an element. This brings about the effect that the correction value of the image signal is generated based on the correction value of the end pixel and the distance from the end to the boundary.

  In the first aspect, the peripheral portion may be a region to be corrected for the image signal. This brings about the effect that the image signal output from the pixel arranged in the peripheral portion becomes a correction target.

  In the first aspect, the correction value generation unit performs linear interpolation based on the held correction value and distance for each pixel arranged between the end pixel and the peripheral boundary pixel. Thus, the correction value may be generated. As a result, the correction value is generated by linear interpolation.

  In the first aspect, the correction value generation unit may perform the linear interpolation by dividing a voltage corresponding to the held correction value with a resistor. As a result, the voltage corresponding to the correction value is divided by the resistor, and linear interpolation is performed.

  In the first aspect, the correction data holding unit holds a correction value of the end pixel arranged in the row direction of the pixel array unit and a distance from the end to the boundary in the row. The correction value generation unit may generate the correction value for each column of the pixel array unit, and the correction unit may perform the correction for each column. As a result, the correction is performed for each column.

  In the first aspect, the correction unit may be arranged for each column, and the plurality of correction units may perform the correction based on the generated correction value for each column. This brings about the effect that correction is performed by the correction unit arranged for each column.

  In the first aspect, the correction data holding unit holds the correction value of the end pixel arranged in the column direction of the pixel array unit and the distance from the end to the boundary in the column. The correction value generation unit may generate the correction value for each row, and the correction unit may perform the correction for each row. This brings about the effect | action that correction | amendment is performed for every line.

  In the first aspect, the correction data holding unit includes a correction value of the end pixel arranged in the row direction and the column direction of the pixel array unit and the end to the boundary in the row and column. The correction value generation unit may generate the correction value for each row and column, and the correction unit may perform the correction for each row and column. This brings about the effect that correction is performed for each row and column.

  Further, in the first aspect, the correction data holding unit is configured so that the correction value of the end pixel relating to one side of the two opposing sides in the pixel array unit and the end portion relating to the one side The distance to the boundary may be stored, and the correction value generation unit may generate the correction value for the two sides based on the stored correction value and distance for the one side. This brings about the effect that the correction value or the like of the other side is generated by the correction value or the like of any one of the two opposing sides in the pixel array section.

  Further, in the first aspect, based on the reference signal generation unit that generates a reference signal that is a reference signal when analog-digital conversion is performed on the image signal output from the pixel, and the generated correction value A reference signal adjustment unit that adjusts the reference signal, and the correction unit may perform the correction by performing the analog-to-digital conversion based on the adjusted reference signal. Thus, the image signal is corrected by performing analog-digital conversion based on the reference signal adjusted based on the correction value.

  In addition, according to a second aspect of the present technology, the pixels that output image signals corresponding to the irradiated light are arranged in a matrix shape and arranged at the peripheral portion of the pixel array portion having a central portion and a peripheral portion. Among the correction values when correcting the image signal output from the pixel, the correction value of the end pixel which is the pixel arranged at the end of the pixel array unit, and the central portion and the peripheral portion from the end portion And a correction data holding unit that holds the distance to the boundary of the pixel, and a peripheral boundary pixel that is a pixel arranged at the boundary based on the held correction value and distance. An imaging apparatus comprising: a correction value generation unit that generates the correction value in each pixel; a correction unit that corrects the image signal based on the correction value; and a processing circuit that processes the corrected image signal. is there. This brings about the effect that the correction value of the image signal is generated based on the correction value of the end pixel and the distance from the end to the boundary.

  According to the present technology, an excellent effect of reducing the amount of correction data when correcting an image signal can be obtained. Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is a figure showing an example of composition of imaging device 10 in a 1st embodiment of this art. It is a figure which shows the structural example of the horizontal drive part 300 in embodiment of this technique. It is a figure showing an example of composition of analog-digital conversion part 310 in an embodiment of this art. It is a figure which shows an example of the analog digital conversion in embodiment of this technique. It is a figure which shows the structural example of the reference signal production | generation part 400 in embodiment of this technique. It is a figure showing an example of composition of reference signal adjustment part 700 in a 1st embodiment of this art. It is a figure showing an example of shading in a 1st embodiment of this art. It is a figure showing an example of amendment of an image signal in an embodiment of this art. It is a figure showing an example of composition of amendment value generation part 600 in a 1st embodiment of this art. It is a figure showing an example of composition of voltage current conversion part 630 in an embodiment of this art. It is a figure showing an example of shading in a 2nd embodiment of this art. It is a figure showing an example of composition of reference signal adjustment part 700 in a 2nd embodiment of this art. It is a figure showing an example of composition of amendment value generation part 600 in a 2nd embodiment of this art. It is a figure showing an example of composition of imaging device 10 in a 3rd embodiment of this art. It is a figure showing an example of composition of reference signal adjustment part 700 in a 3rd embodiment of this art.

Hereinafter, modes for carrying out the present technology (hereinafter referred to as embodiments) will be described. The description will be made in the following order.
1. First embodiment (example in which correction is performed for each column of the pixel array section)
2. Second embodiment (example in which correction is performed for each row of the pixel array section)
3. Third embodiment (example in which correction is performed for each row and column of the pixel array section)

<1. First Embodiment>
[Configuration of imaging device]
FIG. 1 is a diagram illustrating a configuration example of the imaging device 10 according to the first embodiment of the present technology. The imaging apparatus 10 includes a pixel array unit 100, a vertical drive unit 200, a horizontal drive unit 300, a reference signal generation unit 400, a correction data holding unit 500, a correction value generation unit 600, and a reference signal adjustment unit 700. With.

  The pixel array unit 100 generates an image signal corresponding to an image formed by a lens (not shown) or the like and outputs the image signal to the horizontal driving unit 300. The pixel array unit 100 includes pixels 110 that generate image signals arranged in a matrix shape. In addition, the pixel 110 generates an image signal corresponding to light emitted to the pixel 110 by an element that performs photoelectric conversion, such as a photodiode. In addition, an image signal corresponding to desired light can be generated by disposing a filter that transmits light of a predetermined frequency in the pixel 110. For example, an image signal corresponding to red light, green light, or blue light can be generated by disposing red, green, or blue filters in the pixels 110, respectively.

  In the pixel array unit 100, signal lines 101 and signal lines 102 are arranged in an XY matrix. The signal line 101 is a signal line that transmits a control signal to the pixel 110. Based on this control signal, the pixel 110 outputs the generated image signal and the like. The signal line 101 is arranged for each row of the pixel array unit 100 and wired in common to the pixels 110 arranged in one row. That is, a common control signal is transmitted to the pixels 110 arranged in one row. On the other hand, the signal line 102 is a signal line that transmits an image signal generated by the pixel 110. The signal line 102 is arranged for each column of the pixel array unit 100 and wired in common to the pixels 110 arranged in one column. That is, the pixels 110 arranged in one column output an image signal generated for the common signal line 102.

  The vertical driving unit 200 generates control signals for the pixels 110 arranged in the pixel array unit 100. The vertical drive unit 200 generates, for example, a control signal for outputting an image signal to the pixels 110 and outputs the control signal for each row via the signal line 101. As described above, since the signal line 101 is wired in common to the pixels 110 arranged in one row, an image signal is simultaneously output from all the pixels 110 arranged in one row.

  The horizontal driving unit 300 processes an image signal generated by the pixels 110 arranged in the pixel array unit 100. For example, the horizontal driving unit 300 can perform analog-digital conversion processing for converting an image signal generated by the pixel 110 into a digital image signal. The horizontal driving unit 300 in FIG. 1 includes an analog / digital conversion unit 310 that performs this analog / digital conversion. Further, the horizontal driving unit 300 can perform a correction process on the image signal generated by the pixel 110, for example. The horizontal driving unit 300 outputs the processed image signal to the signal line 301. This output image signal corresponds to the output image signal of the imaging device 10. Details of the configuration of the horizontal driving unit 300 will be described later.

  The reference signal generation unit 400 generates a reference signal. Here, the reference signal is a signal that serves as a reference for analog-digital conversion of an image signal. As this reference signal, for example, a signal whose value changes in a ramp shape can be used. The reference signal generation unit 400 starts generating a reference signal in synchronization with the start of analog-digital conversion in the analog-digital conversion unit 310. The reference signal generated by the reference signal generation unit 400 is output to the reference signal adjustment unit 700 via the signal line 401. Details of the configuration of the reference signal generator 400 will be described later.

  The correction data holding unit 500 holds correction data for correcting the image signal output from the pixel 110. The correction data holding unit 500 holds correction data of an image signal for reducing luminance unevenness at a peripheral portion of the screen called shading. As this correction data, for example, a correction value in a pixel (hereinafter referred to as an end pixel) arranged at an end of the pixel array unit 100 and a distance from the end of the pixel array unit 100 to the boundary between the center and the peripheral portion. And can hold. Here, the end portion of the pixel array unit 100 represents the outermost periphery of the pixels 110 arranged in a matrix shape in the pixel array unit 100. Further, the peripheral portion represents a region in the vicinity of the end portion in the pixel array unit 100. This peripheral portion is a target region for image signal correction. That is, the image signal generated by the pixels 110 arranged at the peripheral edge is a correction target. Moreover, the area | region other than a peripheral part corresponds to the above-mentioned center part. Further, the pixels 110 arranged at the boundary between the central part and the peripheral part (hereinafter referred to as the boundary) are referred to as peripheral part boundary pixels.

  The correction data holding unit 500 shown in the figure holds correction data for the pixels 110 arranged in the row direction of the pixel array unit 100. Specifically, the correction value of the end pixel at both ends of the row and the distance from the end to the boundary are held and output to the correction value generation unit 600 via the signal line 501. The difference between the image signals of the end pixel and the peripheral boundary pixel can be applied to the correction value. In this case, the correction data holding unit 500 can output a voltage signal corresponding to the difference as a correction value. As will be described later, the correction data holding unit 500 outputs a positive or negative voltage signal as a correction value. When the correction value is a positive polarity signal, correction for reducing the luminance of the image signal is executed. On the other hand, when the correction value is a negative polarity signal, correction for increasing the luminance of the image signal is executed. In addition, the number of pixels from the end pixel to the peripheral boundary pixel can be applied to the distance. Details of correction in the imaging apparatus 10 will be described later.

  The correction value generation unit 600 generates a correction value for the pixel 110 disposed between the end pixel and the peripheral boundary pixel. The correction value generation unit 600 generates correction values for the pixels 110 arranged in one row of the pixel array unit 100. That is, a correction value is generated for each column of the pixel array unit 100. The generated correction value is output to the reference signal adjustment unit 700 via the signal line 601. Details of the configuration of the correction value generation unit 600 will be described later.

  The reference signal adjustment unit 700 adjusts the reference signal output from the reference signal generation unit 400 based on the correction value output from the correction value generation unit 600. The reference signal adjustment unit 700 adjusts the reference signal for each column of the pixels 110. The adjusted reference signal is output to the horizontal driving unit 300 via the signal line 701. Details of the configuration of the reference signal adjustment unit 700 will be described later.

  The pixel array unit 100, the vertical drive unit 200, the analog / digital conversion unit 310, the reference signal generation unit 400, the correction data holding unit 500, the correction value generation unit 600, and the reference signal adjustment unit 700 constitute an image sensor.

[Configuration of horizontal drive unit]
FIG. 2 is a diagram illustrating a configuration example of the horizontal driving unit 300 according to the embodiment of the present technology. The horizontal drive unit 300 includes an analog / digital conversion unit (AD conversion unit) 310 and an image signal horizontal transfer unit 320.

  The analog / digital conversion unit 310 performs analog / digital conversion on the image signal output from the pixel 110. The analog / digital conversion unit 310 performs analog / digital conversion based on the reference signal output from the reference signal adjustment unit 700. The converted digital image signal is output to the image signal horizontal transfer unit 320 via the signal line 302. As shown in the figure, the analog-digital conversion unit 310 is arranged for each column of the pixel array unit 100. Further, a reference signal is supplied for each of these analog / digital conversion units 310. The analog-digital conversion is simultaneously performed in these analog-digital conversion units 310. Details of the configuration of the analog-digital conversion unit 310 will be described later. The analog-digital conversion unit 310 is an example of a correction unit described in the claims.

  The image signal horizontal transfer unit 320 performs processing for sequentially transferring a plurality of digital image signals output from the analog-digital conversion unit 310. This transfer can be performed, for example, by sequentially outputting to the signal line 301 from the digital image signal output by the analog-digital conversion unit 310 disposed at the left end of FIG. The image signal horizontal transfer unit 320 is an example of a processing circuit described in the claims.

[Configuration of analog-digital converter]
FIG. 3 is a diagram illustrating a configuration example of the analog-digital conversion unit 310 according to the embodiment of the present technology. The analog-digital conversion unit 310 includes capacitors 311 and 312, a comparison unit 313, and a count unit 314.

  Capacitors 311 and 312 are coupling capacitors. The capacitor 311 is connected between the signal line 701 and the comparison unit 313 and transmits the reference signal output by the reference signal adjustment unit 700 to the comparison unit 313. The capacitor 312 is connected between the signal line 102 and the comparison unit 313 and transmits the image signal output from the pixel 110 to the comparison unit 313.

  The comparison unit 313 compares the reference signal and the image signal transmitted by the capacitors 311 and 312. The comparison unit 313 outputs the comparison result to the count unit 314. For example, the comparison unit 313 outputs a value “1” when the voltage of the reference signal is higher than the voltage of the image signal, and compares the value “0” when the voltage of the reference signal becomes lower than the voltage of the image signal. As a result, it can be output.

  The count unit 314 measures the time from the start of analog-digital conversion in the analog-digital conversion unit 310 to the output of the comparison result by the comparison unit 313. The counting unit 314 measures time by counting clock signals (not shown). The count unit 314 holds the count value as a result of analog-digital conversion. Thereafter, the held count value is output to the image signal horizontal transfer unit 320 when the image signal horizontal transfer unit 320 transfers the digital image signal.

[Analog-digital conversion]
FIG. 4 is a diagram illustrating an example of analog-digital conversion according to the embodiment of the present technology. This figure shows the state of analog-digital conversion in the analog-digital conversion unit 310 described in FIG. In the figure, a reference signal and an image signal represent waveforms of the reference signal and the image signal input to the comparison unit 313. Waveforms 391 and 392 in the figure correspond to the waveforms of the reference signal and the image signal, respectively. The output of the comparison unit represents the output (comparison result) of the comparison unit 313. The count value represents the count value of the count unit 314.

  First, reference signal generation in the reference signal generation unit 400 is started. As shown in the figure, the reference signal is a signal whose voltage drops to a ramp shape. At the same time, the counting unit 314 starts counting. At this time, since the voltage of the reference signal is higher than the voltage of the image signal, the output of the comparison unit 313 is a value “1”. Thereafter, when the voltage of the reference signal becomes lower than the voltage of the image signal, the output of the comparison unit 313 transitions to the value “0”. As a result, the counting unit 314 stops counting. The count value at this time is held in the count unit 314. In the figure, the held count value is represented by “A”. Thereafter, the generation of the reference signal in the reference signal generation unit 400 is stopped, and the count value “A” held in the count unit 314 is output to the image signal horizontal transfer unit 320 as a result of the analog-digital conversion. Finally, the count value of the count unit 314 is reset and returns to the initial state. In this way, analog-digital conversion by the analog-digital conversion unit 310 is performed.

[Configuration of reference signal generator]
FIG. 5 is a diagram illustrating a configuration example of the reference signal generation unit 400 according to the embodiment of the present technology. The reference signal generation unit 400 includes a count unit 410 and a digital / analog conversion unit 420.

  The count unit 410 counts a clock signal (not shown) and outputs a count value to the digital / analog conversion unit 420. The count unit 410 starts down-counting in synchronization with the start of analog-digital conversion in the analog-digital conversion unit 310.

  The digital-analog conversion unit 420 converts the count value output from the count unit 410 into a reference signal. The digital / analog conversion unit 420 converts the count value into a reference signal by digital / analog conversion. The digital-analog converter 420 outputs a current whose value decreases in a ramp shape as a reference signal.

[Configuration of reference signal adjustment unit]
FIG. 6 is a diagram illustrating a configuration example of the reference signal adjustment unit 700 according to the first embodiment of the present technology. The reference signal adjustment unit 700 includes a constant current source 710, a MOS transistor 720, and a resistor 730.

  The signal line 401 is commonly connected to the gate of the MOS transistor 720 and one end of the resistor 730, and the other end of the resistor 730 is grounded. The drain of the MOS transistor 720 is grounded. The source of the MOS transistor 720 is connected to one end of the signal line 601, the signal line 701, and the constant current source 710. The other end of the constant current source 710 is connected to the power supply line Vdd. Among these, the constant current source 710 and the MOS transistor 720 are arranged for each analog-digital conversion unit 310 of the horizontal driving unit 300 and are respectively wired to the plurality of signal lines 701. The signal line 601 is also composed of a plurality of signal lines, and is connected to the constant current source 710 and the MOS transistor 720, respectively. On the other hand, the gates of the plurality of MOS transistors 720 are commonly connected to one end of the signal line 401 and the resistor 730.

  The resistor 730 converts the reference signal output as a current whose value changes in a ramp shape from the reference signal generator 400 into a voltage.

  The constant current source 710 supplies a constant current. The constant current source 710 forms a source follower circuit together with the MOS transistor 720.

  The MOS transistor 720 amplifies the reference signal converted into a voltage by the resistor 730. As this MOS transistor 720, a P-channel MOS transistor can be used. The signal line 601 is connected to the source of the MOS transistor 720. A current corresponding to a correction value generated by a correction value generation unit 600 described later is output to the signal line 601. By adding or subtracting the current corresponding to the correction value, the voltage of the source of the MOS transistor 720 can be changed. Thereby, the reference signal can be adjusted. Such correction of the reference signal is individually performed in the plurality of MOS transistors 720, and the corrected reference signal is output via the signal line 701, respectively.

[shading]
FIG. 7 is a diagram illustrating an example of shading according to the first embodiment of the present technology. In the figure, a represents a screen 801 where shading has occurred. In addition, b in the figure represents the relationship between the luminance and the horizontal position in an arbitrary row of a in the figure. In the first embodiment of the present technology, shading in which luminance unevenness in a form in which the luminance at the left and right end portions of the screen and the central portion of the peripheral portion are different is a correction target. In the figure, an example of luminance unevenness in which the left peripheral edge has high luminance and the right peripheral edge has low luminance is shown. Such luminance unevenness in the central portion and the peripheral portion of the screen is caused, for example, by the difference in sensitivity in photoelectric conversion between the peripheral pixel 110 and the central pixel 110 in the pixel array unit 100.

  The dotted line b in the figure represents the luminance at the center of the screen. In the graph 802 of b in the figure, the left end portion has higher luminance and the right end portion has lower luminance than the central portion. By correcting the difference in luminance from the central portion, it is possible to prevent the occurrence of shading. In FIG. 7B, positions 805 and 806 each represent a boundary. A region sandwiched between the positions 805 and 806 is a pixel region that does not require luminance correction. Further, the brightness difference increases as the distance from the positions 805 and 806 approaches the edge, and the difference becomes maximum at the edge of the screen. In b in the figure, the difference in luminance at the end is represented by 803 and 804, respectively. A correction value corresponding to this difference corresponds to a correction value in the end pixel. Further, the pixels 110 arranged at the positions 805 and 806 correspond to the peripheral boundary pixels.

  The correction value of the pixel 110 between the end pixel and the peripheral boundary pixel can be obtained by calculating the approximate value of the graph 802 between the positions 805 and 806 of b in FIG. For example, by performing linear interpolation based on the graph 802, the correction value of the pixel 110 between the end pixel and the peripheral boundary pixel can be calculated. As a result, the data held in the correction data holding unit 500 can be set to four values: the correction value of the end pixel and the distance from the end to the boundary, and the holding capacity of the correction data holding unit 500 can be reduced. Further, as represented by b in the figure, when the left and right positions 805 and 806 are symmetrical, the distance from one end to the boundary can be applied to the other side. Further, since the correction value of the end pixel is also symmetric except for the polarity, the correction value of the other end pixel can be generated based on the correction value of one of the end pixels. That is, it is possible to generate the correction value for the two sides based on the correction value of the end pixel related to one of the two opposite sides of the pixel array unit 100 and the distance from the end to the boundary. In this case, the storage capacity of the correction data storage unit 500 can be further reduced.

  Note that the generation of the correction value in the embodiment of the present technology is not limited to this example. For example, the correction value can be generated by performing quadratic or higher-order polynomial interpolation.

[Correction of image signal]
FIG. 8 is a diagram illustrating an example of image signal correction according to the embodiment of the present technology. This figure shows the waveforms of the reference signal and the image signal and the output waveform of the comparison unit, as in FIG. FIG. 3 shows an image signal and a corrected reference signal when shading occurs.

  In the waveform 392 of the image signal in the same figure, the solid line represents the image signal of the pixel 110 arranged between the positions 805 and 806 of b in FIG. In addition, the dotted line and the alternate long and short dash line represent the image signals of the pixels 110 arranged at the left peripheral portion and the right peripheral portion of b in FIG. In order to correct the change in the level of the image signal, the waveform 391 of the reference signal is adjusted. As shown in the figure, the change in the waveform 392 of the image signal can be canceled by adjusting the level of the reference signal to the level of the dotted line and the alternate long and short dash line in accordance with the change in the image signal. The output can be stabilized. By performing analog-digital conversion based on the output of the comparison unit 313, the influence of shading can be reduced. As described above, in the embodiment of the present technology, the image signal is corrected by performing analog-digital conversion on the image signal based on the reference signal adjusted by the correction value.

[Configuration of Correction Value Generation Unit]
FIG. 9 is a diagram illustrating a configuration example of the correction value generation unit 600 according to the first embodiment of the present technology. The correction value generation unit 600 includes a switching unit 610, a resistor 620, and a voltage / current conversion unit 630. In the figure, the end pixel correction value and the distance represent a voltage signal corresponding to the correction value in the end pixel transmitted by the signal line 501 and the distance from the end to the boundary, respectively. Among these, the end pixel correction value # 1 corresponds to the correction value of the end pixel arranged at the left end of the row of the pixel array unit 100, and the end pixel correction value # 2 is at the right end of the row of the pixel array unit 100. This corresponds to the correction value of the arranged end pixel. Similarly, the distance # 1 represents the distance from the left end of the row of the pixel array unit 100 to the left boundary, and the distance # 2 represents the distance from the right end of the row of the pixel array unit 100 to the right boundary.

  The voltage-current converter 630 converts a voltage corresponding to the correction value into a current. The voltage / current converter 630 is arranged for each MOS transistor 720 described with reference to FIG. 6 and outputs a current corresponding to the correction value via the signal line 601. In addition, end voltage correction values # 1 and # 2 are input to the voltage / current conversion units 630 disposed at the upper and lower ends of the voltage / current conversion unit 630 in FIG.

  The resistor 620 divides a voltage corresponding to the correction value. In the figure, a plurality of resistors 620 are connected in series, and end pixel correction values # 1 and # 2 output from the correction data holding unit 500 are applied to both ends of the resistors 620 connected in series, respectively. The applied correction value is divided by a plurality of resistors 620. The divided voltage is input to the plurality of voltage-current converters 630 described above. Note that the resistance values of the plurality of resistors 620 are assumed to be equal.

  The switching unit 610 selects a connection node of the resistors 620 connected in series and grounds them. The switching unit 610 short-circuits the connection node selected based on the distance # 1 and the distance # 2 output from the correction data holding unit 500 and the ground. Specifically, a switch wired between the connection node and the ground is turned on in accordance with the number of pixels from the end pixel transmitted as the distance. For example, when the distance # 1 is 3 pixels and the distance # 2 is 1 pixel, the switching unit 610 includes 2 switches, the third switch from the top and the bottom switch, among the switches shown in FIG. One is turned on. As a result, among the plurality of voltage-current converters 630 shown in FIG. 6, the voltage-current converters 630 arranged at the second and third from the top are divided by the voltage obtained by dividing the end pixel correction value # 1 ( Correction value) is input. Thereafter, the correction value converted into a current by the voltage / current converter 630 is input to the reference signal adjuster 700.

  On the other hand, the voltage-current converter 630 disposed at the fourth from the top, the voltage-current converter 630 disposed at the lower end, and the inputs of the voltage-current converter 630 disposed therebetween are grounded. Therefore, no current corresponding to the correction value is output from these voltage / current converters 630, and the reference signal adjustment in the reference signal adjustment unit 700 is not executed. In this way, the end pixel correction value is divided by the resistor 620, whereby linear interpolation of the correction value can be performed.

[Configuration of voltage-current converter]
FIG. 10 is a diagram illustrating a configuration example of the voltage-current conversion unit 630 according to the embodiment of the present technology. The voltage / current converter 630 includes a constant current source 639 and MOS transistors 631 to 638. Of these, P-channel MOS transistors can be used as the MOS transistors 631 to 634. For the MOS transistors 635 to 638, N-channel MOS transistors can be used.

  The gate of MOS transistor 635 is connected to signal line 501, and the drain is connected to the gate of MOS transistor 631 and the gate and drain of MOS transistor 632. The source of the MOS transistor 635 is connected to the source of the MOS transistor 636 and one end of the constant current source 639. The other end of the constant current source 639 is grounded. The source of the MOS transistor 632 and the source of the MOS transistor 631 are connected to the power supply line Vdd. The drain of MOS transistor 631 is connected to the drain and gate of MOS transistor 637 and the gate of MOS transistor 638. The sources of the MOS transistor 637 and the MOS transistor 638 are grounded. The drain of the MOS transistor 638 is connected to the signal line 601 and the drain of the MOS transistor 634. The gate of MOS transistor 634 is connected to the gate and drain of MOS transistor 633 and the drain of MOS transistor 636. The sources of MOS transistor 634 and MOS transistor 633 are connected to power supply line Vdd. The gate of the MOS transistor 636 is grounded.

  Also, positive and negative power supplies are supplied from the power supply lines Vdd and Vss, respectively. 9 corresponds to the voltage / current converter 630 arranged at the upper end or the lower end of the voltage / current converter 630 described in FIG. 9. In other voltage-current converter 630, the gate of MOS transistor 635 is connected to the connection node of resistors 620 connected in series in FIG.

  The MOS transistors 635 and 636 and the constant current source 639 in the figure constitute a differential amplifier. Among these, since the gate of the MOS transistor 636 is grounded, the above-described differential amplifier performs amplification with reference to the ground potential. MOS transistors 631 and 632, MOS transistors 633 and 634, and MOS transistors 637 and 638 form a current mirror circuit, respectively. Further, MOS transistors 632 and 633 are connected as drain loads of the MOS transistors 635 and 636 constituting the differential amplifier, respectively. Therefore, a current having a value substantially equal to the drain current of MOS transistor 635 flows to the drains of MOS transistors 632, 631, 637 and 638. The drain current of the MOS transistor 638 is a current that flows in a direction in which a current is drawn from the signal line 601.

  On the other hand, a current substantially equal to the drain current of MOS transistor 636 flows through the drains of MOS transistors 633 and 634. The drain current of the MOS transistor 634 is a current that flows in a direction in which a current is supplied to the signal line 601. For this reason, a current corresponding to the difference between the drain currents of the MOS transistors 635 and 636 constituting the differential amplifier flows through the signal line 601. Specifically, when the voltage of the signal line 501 (the voltage of the gate of the MOS transistor 635) is higher than the ground potential, the drain current of the MOS transistor 638 becomes larger than the drain current of the MOS transistor 634, and the signal line 601 In contrast, a negative current is supplied from the voltage-current converter 630. When the voltage of the signal line 501 is lower than the ground potential, the drain current of the MOS transistor 638 is smaller than the drain current of the MOS transistor 634, and a positive current with respect to the signal line 601 is supplied from the voltage-current conversion unit 630. Supplied.

  In addition, when the voltage of the signal line 501 is equal to the ground potential, the supply of current from the voltage / current converter 630 is stopped. In this way, the voltage corresponding to the correction value is converted into a current by the voltage / current converter 630 and added or subtracted to the source of the MOS transistor 720 described in FIG. 6 to adjust the reference signal. For example, when the waveform 392 of the image signal described in FIG. 8 changes to a signal indicated by a dotted line, a negative-polarity correction value is applied to the input of the voltage-current converter 630 corresponding to the pixel. Thereby, current is added to the source of the MOS transistor 720 in FIG. 6, the reference signal can be adjusted to the waveform 391 of the reference signal indicated by the dotted line in FIG. 8, and the image signal can be corrected. When the waveform 392 of the image signal described in FIG. 8 changes to a signal indicated by a one-dot chain line, a positive correction value is applied to the input of the voltage / current converter 630 corresponding to the pixel.

  As described above, in the first embodiment of the present technology, the pixels arranged in the peripheral portion based on the correction value of the end pixel in the pixel 110 arranged in the row direction and the distance from the end to the boundary. The correction value of the image signal generated by 110 is generated. This can reduce the amount of data when correcting shading that occurs in the horizontal direction of the screen.

[Modification]
In the first embodiment described above, positive and negative voltage signals are used as end pixel correction values, but only positive polarity signals may be used as end pixel correction values. Good. This is because the negative power supply is omitted and the power supply unit of the imaging apparatus 10 has a simple configuration. The modification of the first embodiment of the present technology is different from the first embodiment described above in that only a positive signal is used as the correction value of the end pixel.

  In the switching unit 610 of the correction value generation unit 600 described with reference to FIG. 9, instead of short-circuiting the connection node of the resistor 620 and the ground, a predetermined reference voltage is supplied to the node. Further, the above-described reference voltage is applied to the gate of the MOS transistor 636 of the voltage-current converter 630 described in FIG. 10, and the power supply line Vss is changed to ground. Further, the correction data holding unit 500 described in FIG. 1 outputs a voltage signal obtained by adding a reference voltage to a voltage corresponding to the held correction value of the end pixel. As a result, a bias voltage corresponding to the reference voltage is added, and a negative polarity correction value can be converted into a positive polarity signal.

  As described above, according to the modification of the first embodiment of the present technology, the negative power supply can be omitted, and the configuration of the imaging device 10 can be simplified.

<2. Second Embodiment>
In the first embodiment described above, the image signal is corrected for each column. On the other hand, you may correct | amend an image signal for every line. The second embodiment of the present technology is different from the first embodiment in that the influence of shading that occurs in the vertical direction of the screen is reduced by correcting the image signal for each row.

[shading]
FIG. 11 is a diagram illustrating an example of shading according to the second embodiment of the present technology. The figure shows the relationship between the luminance and the vertical position in an arbitrary column of the screen. In the second embodiment of the present technology, shading in which luminance unevenness in a form in which the luminance is different between the upper and lower end portions of the screen and the central portion of the peripheral portion is a correction target. A graph 812 in the figure is a graph showing the relationship between the luminance and the vertical position, and shows an example of luminance unevenness in which the upper and lower peripheral portions have higher luminance than the central portion. In the figure, positions 815 and 816 represent boundaries. Differences 813 and 814 represent the luminance difference between the edge and the boundary. Also in this figure, since the shape of the graph 812 is symmetric, the end pixel of the other side is based on the correction value of the end pixel of one of the upper and lower sides and the distance from the end to the boundary. Correction values and the like can be generated.

[Configuration of reference signal adjustment unit]
FIG. 12 is a diagram illustrating a configuration example of the reference signal adjustment unit 700 according to the second embodiment of the present technology. The reference signal adjustment unit 700 in FIG. 6 is different from the reference signal adjustment unit 700 described in FIG. 6 in that it includes a set of constant current sources 710 and a MOS transistor 720. In the figure, the adjusted reference signal is output via a single signal line 701.

  Further, in the horizontal driving unit 300 according to the second embodiment of the present technology, the signal line 701 is wired in common to all the analog-digital conversion units 310, and the above-described adjusted reference signal is input in common. .

[Configuration of Correction Value Generation Unit]
FIG. 13 is a diagram illustrating a configuration example of the correction value generation unit 600 according to the second embodiment of the present technology. The correction value generation unit 600 of FIG. 9 further includes a selection unit 640 and differs from the correction value generation unit 600 described with reference to FIG. 9 in that it includes one voltage-current conversion unit 630.

  The selection unit 640 selects end correction values and the like. The selection unit 640 includes a connection node of the resistor 620 connected in series with the signal line to which the end pixel correction value # 1 of the signal line 501 is transmitted and the end pixel correction value # of the signal line 501. 2 is connected to a signal line to which 2 is transmitted. Then, the selection unit 640 sequentially selects the above-described connection nodes or signal lines in synchronization with the execution of the analog-digital conversion for each row in the horizontal driving unit 300, and selects the end pixel correction value or the divided correction value as the voltage. Output to the current converter 630. Thereby, the image signal can be corrected for each row.

  The voltage-current conversion unit 630 in FIG. 6 converts the end pixel correction value output from the selection unit 640 into a current, and outputs the current to the reference signal adjustment unit 700 via the single signal line 601. .

  In addition, the correction data holding unit 500 according to the second embodiment of the present technology holds correction data in the pixels 110 arranged in the column direction of the pixel array unit 100. Specifically, the correction value of the end pixel at both ends of the column and the distance from the end to the boundary are held and output via the signal line 501.

  The other configuration of the imaging apparatus 10 is the same as that of the imaging apparatus 10 described in the first embodiment of the present technology, and thus the description thereof is omitted.

  As described above, in the second embodiment of the present technology, the pixel 110 arranged in the column direction is arranged at the peripheral portion based on the correction value of the end pixel and the distance from the end to the boundary. A correction value of the image signal generated by the pixel 110 is generated. Thereby, it is possible to reduce the amount of data when correcting shading generated in the vertical direction of the screen.

<3. Third Embodiment>
In the first embodiment described above, the image signal is corrected for each column. On the other hand, the image signal may be corrected for each row and column. The third embodiment of the present technology differs from the first embodiment in that the influence of shading that occurs in the horizontal and vertical directions of the screen is reduced by correcting the image signal for each row and column. .

[Configuration of imaging device]
FIG. 14 is a diagram illustrating a configuration example of the imaging device 10 according to the third embodiment of the present technology. The imaging apparatus 10 in the figure is different from the imaging apparatus 10 described in FIG. 1 in that a column correction value generation unit 910 and a row correction value generation unit 920 are provided instead of the correction value generation unit 600.

  The column correction value generation unit 910 generates a correction value for each column. The column correction value generation unit 910 outputs the generated correction value to the reference signal adjustment unit 700 via the signal line 601. The column correction value generation unit 910 can use the correction value generation unit 600 described with reference to FIG.

  The row correction value generation unit 920 generates a correction value for each row. The row correction value generation unit 920 outputs the generated correction value to the reference signal adjustment unit 700 via the signal line 602. As the row correction value generation unit 920, the correction value generation unit 600 described in FIG. 13 can be used.

  A correction data holding unit 500 shown in FIG. 5 holds correction data in the pixels 110 arranged in the row direction and the column direction of the pixel array unit 100. Among these, the correction data in the pixels 110 arranged in the row direction is output to the row correction value generation unit 920 via the signal line 503. Further, correction data in the pixels 110 arranged in the column direction is output to the column correction value generation unit 910 via the signal line 502.

  The column correction value generation unit 910 and the row correction value generation unit 920 are examples of the correction value generation unit described in the claims.

[Configuration of reference signal adjustment unit]
FIG. 15 is a diagram illustrating a configuration example of the reference signal adjustment unit 700 according to the third embodiment of the present technology. 6 differs from the reference signal adjustment unit 700 described in FIG. 6 in that correction values from the column correction value generation unit 910 and the row correction value generation unit 920 are input. The correction value for each column output from the column correction value generation unit 910 is transmitted through the signal line 601 similarly to the reference signal adjustment unit 700 in FIG. On the other hand, a signal line 602 is wired to the reference signal adjustment unit 700 of FIG. The signal line 602 is wired to a connection node between the signal line 401 and the resistor 730. Therefore, the current corresponding to the correction value for each row output from the row correction value generation unit 920 is added to or subtracted from the current corresponding to the reference signal output from the reference signal generation unit 400. Thereby, the reference signal can be adjusted for each row. The reference signal adjusted for each row is commonly applied to the gates of the plurality of MOS transistors 720 and adjusted for each column. Thereby, the imaging device 10 according to the third embodiment of the present technology can correct the image signal for each row and column, and can reduce the influence of shading that occurs in the horizontal and vertical directions of the screen. it can.

  The other configuration of the imaging apparatus 10 is the same as that of the imaging apparatus 10 described in the first embodiment of the present technology, and thus the description thereof is omitted.

  As described above, according to the third embodiment of the present technology, the row correction value generation unit 920 and the column correction value generation unit 910 are arranged to generate respective correction values for each row and column. The shading generated in the horizontal and vertical directions can be corrected.

  The above-described embodiment shows an example for embodying the present technology, and the matters in the embodiment and the invention-specific matters in the claims have a corresponding relationship. Similarly, the invention specific matter in the claims and the matter in the embodiment of the present technology having the same name as this have a corresponding relationship. However, the present technology is not limited to the embodiment, and can be embodied by making various modifications to the embodiment without departing from the gist thereof.

  Further, the processing procedure described in the above embodiment may be regarded as a method having a series of these procedures, and a program for causing a computer to execute these series of procedures or a recording medium storing the program. You may catch it. As this recording medium, for example, a CD (Compact Disc), an MD (MiniDisc), a DVD (Digital Versatile Disc), a memory card, a Blu-ray disc (Blu-ray (registered trademark) Disc), or the like can be used.

  In addition, the effect described in this specification is an illustration to the last, Comprising: It does not limit and there may exist another effect.

In addition, this technique can also take the following structures.
(1) An image signal output from the pixels arranged at the peripheral portion of a pixel array portion having a central portion and a peripheral portion in which pixels that output an image signal corresponding to the irradiated light are arranged in a matrix shape. Of the correction values for correction, the correction values of the end pixels, which are the pixels arranged at the end portions of the pixel array portion, and the distances from the end portions to the boundaries of the central portion and the peripheral portion are held. A correction data holding unit to perform,
A correction value generating unit that generates the correction value in a pixel disposed between the edge pixel and a peripheral boundary pixel that is a pixel disposed on the boundary based on the held correction value and distance;
An imaging device comprising: a correction unit that corrects the image signal based on the correction value.
(2) The imaging device according to (1), wherein the peripheral portion is a region to be corrected for the image signal.
(3) The correction value generation unit performs the linear interpolation based on the held correction value and distance for each pixel arranged between the end pixel and the peripheral boundary pixel, thereby obtaining the correction value. The imaging device according to (1) to be generated.
(4) The imaging device according to (3), wherein the correction value generation unit performs the linear interpolation by dividing a voltage corresponding to the held correction value by a resistor.
(5) The correction data holding unit holds the correction value of the end pixel arranged in the row direction of the pixel array unit and the distance from the end to the boundary in the row,
The correction value generation unit generates the correction value for each column of the pixel array unit,
The imaging device according to any one of (1) to (4), wherein the correction unit performs the correction for each column.
(6) The imaging device according to (5), wherein the correction unit is arranged for each column, and the plurality of correction units respectively perform the correction based on the generated correction value for each column.
(7) The correction data holding unit holds a correction value of the end pixel arranged in the column direction of the pixel array unit and a distance from the end to the boundary in the column,
The correction value generation unit generates the correction value for each row,
The imaging device according to any one of (1) to (4), wherein the correction unit performs the correction for each row.
(8) The correction data holding unit holds the correction value of the end pixel arranged in the row direction and the column direction of the pixel array unit and the distance from the end to the boundary in the row and column. ,
The correction value generation unit generates the correction value for each row and column,
The imaging device according to any one of (1) to (4), wherein the correction unit performs the correction for each row and column.
(9) The correction data holding unit calculates a correction value of the end pixel relating to one of two opposing sides in the pixel array unit and a distance from the end to the boundary relating to the one side. Hold and
The image sensor according to any one of (1) to (8), wherein the correction value generation unit generates the correction value for the two sides based on the correction value and distance for the held one side.
(10) a reference signal generation unit that generates a reference signal, which is a reference signal when analog-digital conversion is performed on the image signal output from the pixel;
A reference signal adjusting unit that adjusts the reference signal based on the generated correction value;
The imaging device according to any one of (1) to (9), wherein the correction unit performs the correction by performing the analog-to-digital conversion based on the adjusted reference signal.
(11) Image signals output from the pixels arranged in the peripheral portion of a pixel array unit having pixels that output image signals corresponding to the irradiated light are arranged in a matrix and have a central portion and a peripheral portion. Of the correction values for correction, the correction values of the end pixels, which are the pixels arranged at the end portions of the pixel array portion, and the distances from the end portions to the boundaries of the central portion and the peripheral portion are held. A correction data holding unit to perform,
A correction value generating unit that generates the correction value in a pixel disposed between the edge pixel and a peripheral boundary pixel that is a pixel disposed on the boundary based on the held correction value and distance;
A correction unit that corrects the image signal based on the correction value;
An image pickup apparatus comprising: a processing circuit that processes the corrected image signal.

DESCRIPTION OF SYMBOLS 10 Imaging device 100 Pixel array part 110 Pixel 200 Vertical drive part 300 Horizontal drive part 310 Analog digital conversion part 311 and 312 Capacitor 313 Comparison part 314 and 410 Count part 320 Image signal horizontal transfer part 400 Reference signal generation part 420 Digital analog conversion part 500 correction data holding unit 600 correction value generation unit 610 switching unit 620, 730 resistance 630 voltage current conversion unit 639, 710 constant current source 640 selection unit 700 reference signal adjustment unit 910 column correction value generation unit 920 row correction value generation unit

Claims (11)

When correcting the image signal output from the pixel arranged in the peripheral portion, which is a region in the vicinity of the end of the pixel array portion in which the pixel that outputs the image signal corresponding to the irradiated light is arranged in a matrix shape Among the correction values, the correction value of the end pixel, which is the pixel arranged at the end of the pixel array unit, and the boundary between the peripheral portion and the region other than the peripheral portion in the pixel array unit to the end A correction data holding unit that holds the distance of
A correction value generating unit that generates the correction value in a pixel disposed between the edge pixel and a peripheral boundary pixel that is a pixel disposed on the boundary based on the held correction value and distance;
An imaging device comprising: a correction unit that corrects the image signal based on the correction value.   The imaging device according to claim 1, wherein the peripheral portion is a region to be corrected for the image signal.   The correction value generation unit generates the correction value by performing linear interpolation based on the held correction value and distance for each pixel arranged between the end pixel and the peripheral boundary pixel. Item 2. The imaging device according to Item 1.   The imaging device according to claim 3, wherein the correction value generation unit performs the linear interpolation by dividing a voltage corresponding to the held correction value by a resistor. The correction data holding unit holds the correction value of the end pixel arranged in the row direction of the pixel array unit and the distance from the end to the boundary in the row,
The correction value generation unit generates the correction value for each column of the pixel array unit,
The imaging device according to claim 1, wherein the correction unit performs the correction for each column.   The imaging device according to claim 5, wherein the correction unit is arranged for each column, and the plurality of correction units respectively perform the correction based on the generated correction value for each column. The correction data holding unit holds the correction value of the end pixel arranged in the column direction of the pixel array unit and the distance from the end to the boundary in the column,
The correction value generation unit generates the correction value for each row,
The imaging device according to claim 1, wherein the correction unit performs the correction for each row. The correction data holding unit holds correction values of the end pixels arranged in a row direction and a column direction of the pixel array unit and a distance from the end part to the boundary in the row and column,
The correction value generation unit generates the correction value for each row and column,
The imaging device according to claim 1, wherein the correction unit performs the correction for each row and column. The correction data holding unit holds a correction value of the end pixel relating to one of two opposing sides in the pixel array unit and a distance from the end to the boundary relating to the one side,
The imaging device according to claim 1, wherein the correction value generation unit generates the correction values for the two sides based on the correction value and distance for the held one side. A reference signal generation unit that generates a reference signal that is a reference signal when performing analog-digital conversion on the image signal output from the pixel;
A reference signal adjusting unit that adjusts the reference signal based on the generated correction value;
The imaging device according to claim 1, wherein the correction unit performs the correction by performing the analog-to-digital conversion based on the adjusted reference signal. When correcting the image signal output from the pixels arranged in the peripheral portion of the pixel array portion having a central portion and a peripheral portion in which pixels that output an image signal corresponding to the irradiated light are arranged in a matrix shape Correction data that holds the correction value of the end pixel that is the pixel arranged at the end of the pixel array portion and the distance from the end to the boundary between the end and the central portion A holding part;
A correction value generating unit that generates the correction value in a pixel disposed between the edge pixel and a peripheral boundary pixel that is a pixel disposed on the boundary based on the held correction value and distance;
A correction unit that corrects the image signal based on the correction value;
An image pickup apparatus comprising: a processing circuit that processes the corrected image signal.

Images